U.S. Pat. No. 4,716,144 is directed to a hydrophilic dye barrier layer located between the dye layer and the subbing layer which is coated on a support of a dye-donor element for thermal dye transfer. There is no disclosure in this patent that teaches a hydrophilic dye-barrier/subbing layer comprising a mixture of polyvinyl alcohol and polyvinylpyrrolidone.
U.S. Pat. No. 4,700,208 is directed to a dye-donor element for thermal dye transfer comprising a hydrophilic dye-barrier/subbing layer located between a dye layer and a support layer. There is no disclosure in this patent that teaches a hydrophilic dye-barrier/subbing layer comprising a mixture of polyvinyl alcohol and polyvinylpyrrolidone.
Japanese Kokai Publication No. 62/128792 discloses a heat transfer sheet for thermal dye transfer printing. The sheet has a dye-transfer-preventative layer comprising more than 60 weight percent of a cellulosic resin or polyvinyl alcohol mixed with a polyester resin. The subject publication does not disclose or suggest a subbing/barrier layer comprising a mixture of polyvinyl alcohol and polyvinyl pyrrolidone in the range claimed.